1. Technical Field
The present invention relates to a method for mounting an integrated circuit having a plurality of leads on a printed circuit board, and particularly to an apparatus and process of effectively and efficiently mounting an integrated circuit of a tape carrier package (TCP) type on a printed circuit board (PCB).
2. Related Art
Most semiconductor electronic devices are now packaged with their integrated circuit components mounted on printed circuit boards (PCB). Integrated circuit packages are generally planar and contain a plurality of leads projecting laterally and generally downward therefrom. These leads, in turn, are soldered to respective circuit pads on a printed circuit board (PCB). Packing techniques for integrated circuit (IC) chips of high functions such as 8086 of 8-bit processor to 80386, 80486 and 80586 of 32-bit processors through 80286 of 16-bit processors, are generally known to satisfy demands for miniaturization in the semiconductor industry. As the chip densities and sophistication of electronic components become greater, however, the precision required in mounting and connecting the leads of the IC chip to the printed circuit board (PCB) substrate become more critical.
Contemporary IC mounting techniques on printed circuit boards (PCB) are disclosed, for example, in U.S. Pat. No. 4,116,376 for Method Of Mounting Integrated Circuit Chips On A Substrate And Apparatus For Carrying Out The Method issued to Delorme et al., U.S. Pat. No. 5,046,953 for Method And Apparatus For Mounting An Integrated Circuit On A Printed Circuit Board issued to Shreeve et al., U.S. Pat. No. 5,235,407 for System For Placement And Mounting Of Fine Pitch Integrated Circuit Devices issued to Spigarelli et al., Adams, Jr. et al., U.S. Pat. No. 5,303,122 for Printed Circuit Board Having A Commonized Mounting Pad Which Different Sized Surface Mounted Devices Can Be Mounted issued to Adams, Jr. et al., U.S. Pat. No. 5,313,368 for Electrical Connections Between Printed Circuit Boards And Integrated Circuits Surface Mounted Thereon issued to Volz et al., U.S. Pat. No. 5,471,310 for System For Placement And Mounting Of Fine Pitch Integrated Circuit Devices issued to Spegarelli et al., U.S. Pat. No. 5,563,380 for Apparatus For Mounting Integrated Circuit Chips On A Mini-Board issued to Rostoker et al., U.S. Pat. No. 5,652,462 for Multilevel Semiconductor Integrated Circuit Device issued to Matsunaga et al., and U.S. Pat. No. 5,667,129 for IC Component Mounting Method And Apparatus issued to Morita et al. Generally, the IC chip is directly mounted on the printed circuit board (PCB), and the leads of the IC chip are soldered or electrically connected to the substrate lead pattern by using direct wire bonding. However, direct wire bonding has not always been reliable. Precise alignment which requires expensive equipment is necessary to prevent solder bridging between the leads of the IC chip and the substrate lead pattern. Moreover, the leads of IC chip are not always uniformly connected to the substrate lead pattern. These production difficulties reduce efficiency and increase cost.
Recent technology for mounting IC chips of higher functions such as Pentium (TM) processor on printed circuit boards (PCB) has been developed. One example of this technology is disclosed in U.S. Pat. No. 5,647,750 for Socket For A Tape Carrier Package issued to Tran et al., in which the IC chip is housed in a tape carrier package (TCP), and is mounted directly on a dielectric tape such as polyimide. Typically, the IC of TCP type has a very small compartment which includes 320 pins and has a spacing of 0.2 mm between the leads. The IC chip is formed without wire bonding which is used in conventional IC chips. As a result, as the size of the IC chip is small, the size of the printed circuit board (PCB) can be even smaller. While the recent method of mounting the IC chip of TCP type eliminates the use of wire bonding, there is still a problem of efficiency. The mounting technique, as I have observed, takes too much time, as the flux must be spread on the lead pattern on the PCB one by one. Moreover, during manufacture, the alignment time between the leads of the IC chip and the lead patterns of the PCB is generally slow, and therefore results in inefficient production.